The basic equation for weight loss that we've all long understood goes a little something like this: eat less food + exercise = lose weight.

And while the exercise part still stands, a study done in 2018 published in the Journal of the American Medical Association suggests weight loss actually has a lot less to do with smaller portion sizes and reduced calorie intake than we first thought. Instead, the study revealed that ditching refined grains, highly processed foods and foods with added sugar was actually the key to shedding the pounds.

If you focus on eating a vegetable-rich diet consisting of mainly whole foods, it seems portion size and calorie content doesn't even come into it.

The research, which was carried out by Christopher D. Gardner, director of nutrition studies at the Stanford Prevention Research Center, assessed around 600 people. The subjects were split them into two diet groups — one eating "healthy" low carb and the other eating "healthy" low fat. Throughout the duration of the study, dietitians trained both test groups to eat home-cooked whole food that was minimally processed and highly nutritious.

Both groups lost a significant amount of weight. Members of the low-carb group tended to lose just over 13 pounds, while those in the low-fat group lost a little less, at an average of 11.7 pounds. Both groups noted reductions in their waist sizes and body fat percentages, as well as in their blood pressure and blood sugar levels.

And they did all that without reducing the amount of food they ate; it was all about controlling the quality and wholesomeness of their food. This was something that shocked the participants, Gardner noted. "A couple (of) weeks into the study people were asking when we were going to tell them how many calories to cut back on," he said.

So it goes to show, it really is about quality not quantity. If you're hungry: eat. Eat as much as you want, just make sure it's the right stuff.